Hello Raph, The short answer to your question is yes, the ADPCM format is supported in USBAudio.sys though we have not had any devices to thoroughly test it with. Thanks, DJ Sisolak Microsoft Corp. This posting is provided "AS IS" with no warranties, and confers no rights. ________________________________ From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Raphael Lamy Sent: Monday, March 22, 2004 8:49 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] USB and ADPCM data format Dear All, I develop a USB audio device and I need to use a ADPCM data format. I just need to know if it is possible to use this format without to write a custom driver (maybe just using usbaudio.sys and Ks.sys). Which are the real datas to send from the USB chip to windows ? Thanks in advance Raph